Thin-walled hollow wheels with internal and external toothing, and apparatus and method for manufacturing the same

Abstract

In a method for manufacturing a hollow wheel which includes an internal toothing and an external toothing, wherein the internal toothing is a gear toothing, a workpiece is machined by way of a stamping tool. The workpiece has a tubular section with a longitudinal axis and a first stabilisation section for the shape stabilisation of the tubular section during the machining. The tubular section is inserted into a die having an internal die toothing. The workpiece is machined on the inner side by the stamping tool so as to simultaneously produce internal and external toothing by way of the workpiece executing a rotation movement with a temporally varying rotation speed and the stamping tool executing radially oscillating movements that are synchronised with the rotation movement.

The invention claimed is: 
     
       1. A method for manufacturing a hollow wheel which comprises an internal toothing and an external toothing, wherein the internal toothing is a gear toothing, the method comprising:
 providing a workpiece to be machined with at least one stamping tool, wherein the workpiece comprises a tubular section with a longitudinal axis as well as at least one first stabilization section which is connected to the tubular section for shape stabilization of the tubular section during the machining with the at least one stamping tool, 
 providing a die for receiving the tubular section, the die comprising a tubular opening in which an internal die toothing is provided, 
 inserting the tubular section into the tubular opening, and 
 machining the workpiece on the inner side of the tubular section inserted into the tubular opening with the at least one stamping tool to simultaneously produce the internal toothing and external toothing, wherein during the machining, the workpiece executes a rotation movement with a temporally varying rotation speed about said longitudinal axis and the at least one stamping tool executes radially oscillating movements which are synchronized with said rotation movement so that the at least one stamping tool forms the tubular section into the die toothing to produce the external toothing and to simultaneously produce the internal toothing with repeated hammering machining of the tubular section, wherein the radially oscillating movements are aligned perpendicular to the longitudinal axis. 
 
     
     
       2. The method according to  claim 1 , wherein a material thickness of the workpiece in the tubular section is less than twice a toothing depth of the internal toothing, before the insertion of the tubular section into the tubular opening. 
     
     
       3. The method according to  claim 1 , wherein the at least one stamping tool comprises an active region which comprises a tool head and two tool flanks adjoining the tool head. 
     
     
       4. The method according to  claim 3 , wherein the tool flanks are shaped such that the internal toothing has a longitudinal crowning. 
     
     
       5. The method according to  claim 3 , wherein the at least one stamping tool comprises two calibrating regions adjoining one of the two tool flanks each and having a shape which is a negative of a shape of a section of a tooth tip of the internal toothing. 
     
     
       6. The method according to  claim 3 , wherein the active region has a shape which is a negative of a shape of a tooth gap of the internal toothing. 
     
     
       7. The method according to  claim 1 , wherein the first stabilization section forms a non-toothed collar of the hollow wheel, said collar forming a unitary part together with the tubular section and being directed towards the longitudinal axis or away from the longitudinal axis. 
     
     
       8. The method according to  claim 1 , wherein
 the first stabilization section has a maximal distance to the longitudinal axis which is larger than a maximal distance the tubular section has to the longitudinal axis by at least 0.25 times a toothing depth of the internal toothing; 
 or 
 the first stabilization section has a minimal distance to the longitudinal axis which is smaller than a minimal distance the tubular section has to the longitudinal axis by at least 0.25 times a toothing depth of the internal toothing. 
 
     
     
       9. The method according to  claim 8 , wherein
 the first stabilization section has an outer diameter which is larger than an outer diameter of the tubular section by at least 0.5 times a toothing depth of the internal toothing; 
 or 
 the first stabilization section has an inner diameter which is smaller than the inner diameter of the tubular section by at least 0.5 times a toothing depth of the internal toothing. 
 
     
     
       10. The method according to  claim 1 , wherein the first stabilization section forms a peripheral end-face of the hollow wheel which is angled with respect to the tubular section. 
     
     
       11. The method according to  claim 10 , the first stabilization section describes an annular shape or a rotationally symmetrical truncated cone shell shape. 
     
     
       12. The method according to  claim 1 , wherein the workpiece comprises a second stabilization section and wherein at least one of the two stabilization sections is directed towards the longitudinal axis. 
     
     
       13. The method according to  claim 1 , wherein the internal toothing is designed as a full-depth toothing with a toothing depth of more than 2.0 times a normal module of the internal toothing. 
     
     
       14. The method according to  claim 1 , wherein a toothing depth of the external toothing is smaller than a toothing depth of the internal die toothing and is smaller than a toothing depth of the internal toothing. 
     
     
       15. The method according to  claim 1 , wherein the internal toothing is a spur toothing or a helical toothing or a herringbone toothing. 
     
     
       16. The method according to  claim 1 , wherein a material thickness of the workpiece in the tubular section is less than 1.5 times a toothing depth of the internal toothing, before the insertion of the tubular section into the tubular opening. 
     
     
       17. The method according to  claim 1 , wherein the internal toothing is designed as a full-depth toothing with a toothing depth of at least 2.4 times a normal module of the internal toothing. 
     
     
       18. A method for manufacturing a planetary gear, comprising manufacturing the hollow wheel according to the method of  claim 1 , and further comprising providing at least one externally toothed gearwheel and inserting of the gearwheel into the hollow wheel.